Porcelain enamels for light metals



V tempetaturespsed toporcelainenarn'el temperatures jso. .lowfthatthe.applicationof.theiporcelain.

United- Donald-1M; d, Clev la d-"m? it 351!!! Corporation, Cleveland,Ohio a corporation f 0 no nawa z 'Applicatioiixu giistllfill57 H vSerial No. 677,231

7 claims? ftci 103548 L Murine Ifhis .'1 nvent1on relates as indicate toporcelain enamels forglight ngetals and has particular reference toresist; ant proteptivga d d t celaifiifahilsfor alunii num-.= n..aluminl l zlflumerous attertriiptshave beeh fiiadeinthepa'stt'o tectand/ or decorate aluminum aiid'i't's 'alloysI HoWever,

vthese P io art p rce ain n mels ar allwha amk PWH.

as leadbearing andlcontaint-he asic toxic efiects inherent in .all' leadcontaining, porcelain ,enarnels; Ihettempera;

tures at which porcelainenameling of aluminum audits ni and additional pnot. contain alliaupxiae.

obtainl a; frit wil temperature. "S

9 obtain a fri';

alloys would be permissible, are much lower than those. a V

st r n an W 11; Thus lead has been used to produc porcelain enamelshavin'g'agmaturing temperature compatible aluminum.

I havelnow. discovered certain new and irnpro alkali :containingporcelain enamel'Icongposit' h1cha e de a turi tempsra q eisdfiiptflbwithihe melting temperature of aluminum and which may proved porcelainenamels. for. application to aluminum and its alloysiwhicharelead-freera.

It is another objectx of. this. invention ,to' rproducezhigh" containingporcelain enamen .Whichare ;.lead-.fre1e and which may the; applied. toaluminum andits ,galloy's gat enamel to the metal needfnotdamage anyspecial. metale lurgic'alpropertiesiofthe-metal; gall. 1. I

It' is'a fur-therlobjec't of this invention tozpmvide .porceg. lainenamelcompositions which aretlead-free, fluorine=free and which.cansb'eufused. to aluminum ,a'n'dsits. alloys: at r a temperaturebetween 900 F. and l050 F. and which will furnish Ta durable smoothglossy coating.

-Otheriobjects will become apparent asthe description p rdc'eeds'i M I Ia a To the accomplishment. .of .the ioregoing randflrela'ted ends, saidinventiom then comprises "the. features .herin-f after fully described.andpartichlarlymointed 40111. in ;th'eJ claims, .the -following.description .settingforth in. detaili certainillustrative,.emb;odiments. o-thejnvention, these; being indicative,however, 10f. huts afe.w of lthemvarigilsil ways in which the principleof the i'nyention may be em- .60 'ployedm. u

V -Broadly stated this inventi enirifirises a lead-free" porcelainenamel having afiring temperature- 'ofi he tweeri Q F. and-21050 F.'.which consists esser'itiallyg'of the following constituents? calculatedas fin/eight; r percn'tages z' 65 zQr 2 3 ..f. RRQBLHII yis there anabsence of j elements but thelprono eXceed;5 .0% and there is Qiihefo'the'r hand, theR O porcelain enamels the is is y 'nggoperation. Thev v rhir'ci'ii t 7W. 7-" 1 porcelain .enarriel.' The j v ririportant ina controlling during firing, thereaction between the porce laiijeiiahieland the aluminum Work piece, they also i e gfijhdit'earing' and spallingresistance propertiesto the porcelain enamel andadditionally=-contributeto the glossy si nage of the fired-piece; --TheSiO is "the glass former:and the-TiO gives'the porcelaimenamel' chemical dur ability or what isknown as acid resistance. Additionally the T10 servesftogiverefractoriness to the/composition;

In th e event it, isv .fQunddesir'a ble to adjust the amounts 1 of the.variouslingrdientsbf the present porcelain enamels for hest results,will;

e V found. expedient to bear the fol-' lowing factor s ininind anaem a9f; .11; wiifi beiein at 5. w he 4 wetghtpercentof'TiO should be keptbetween 0.8 and;

-.--raintedfremiss-1960 i a contrast with esen p9 elam enamels do R dfine; ,p nt'w ii r mew. o B2 3;

fee "porcelain ....P Y for application to aluminum and uminuin basealloys.

(2) The ratio of the weight percent of Sb O 'to the weight percent of Bshould be kept between 1.2 and 8.5; and

(3) The Li O should be about 918% of the total alkali oxide content, theN320 about 30-50% of the total alkali oxide content and the K20 about32-56% of the total alkali oxide content.

which consists essentially of the following constituents calculated asweight percentages:

The ingredients used in making up a batch composition soda ash, antimonyoxide may be substituted for .sodium antimonate, etc., it being(understood, that theamounts of such altered raw materials arecalculated toyield the desiredfrit composition. I I

'In' the preparation of these frits the raw materials are weighed andthoroughly mixed. The mixed batch is then smelted either in a batch typeor a continuous'type smelter and smelted to a homogeneous. glass.Smelting temperatures may vary within wide limits, however, 2100 F.-

23 00 F. is a particularly suitable range. The molten glass is thenfritted with air or water by any of the well known methods.

- The frit is then wet ground or dry ground, with suitable mill additionagents infla ballmill or other mill to a predetermined fineness. 'Thecompositions of our invention produce substantially white semi-opaqueporcelain enamels. If an opaque or colored porcelain enamel is desiredit is convenient, during the, grinding operation to add the desiredopacifying agents (such as TiO orcoloring pigments in addition to thenormally used suspending agents, bonding agents, etc.

The milled frit which has been suspended in a suitable vehicle may beapplied to the aluminum work piece by any of the well known proceduresof spraying, dipping, slushing, brushing,.etc.

After application of the powdered frit to the aluminum work piece it isfiredfor several minutes in a suitable furnace in order to fuse the fritonto the surface ofthe work piece. The firing temperatures are notcritical since the compositions of my invention mature at from 900 F. to1050" F. The temperature used in melting or fusing the frit onto thework piece depends to some extent on the particular aluminum alloy beingcoated and on the particular porcelain enamel composition selected.

Other modes of applying the principle of the invention may be employed,change being made as regards thedetails described, provided the featuresstated in any of the following claims or the equivalent of such beemployed.

1, therefore, particularly point out and distinctly claim as myinvention:

1. A lead-free, alumina-free poreclain enamel having a firingtemperature range of between 900 F. and 1050* F. which consistsessentially of the following constituents calculated as weightpercentages:

where R 0 represents the oxides Na, K and Li; R 0 represents the oxideof B; R 0 represents the oxides of P and Sb; and R0 represents theoxides of Si and Ti, the summation of the weight percentages of R 0, R 0R 0 and R0 ingredients equalling 100%.

2. A lead-free, alumina-free porcelain enamel having a firingtemperature range of between 900 F. and '1050 F.

Percent R 0 21-35 R 0 2- 5 R 0 11-21 R0 44-50 where R 0 represents theoxides Na, K and Li; R 0 represents the oxide of B; R 0 represents theoxides of P and Sb; and R0 represents the oxides of Si' and Ti,

wherein the U 0 is about 918% of the total R 0 content,

the Na O is about 30-50% of the total R 0 content and the K 0 is about32-56% of the totalR O content, the

summation of the weight percentages of R 0, R 0 R 0 and R0 ingredientsequalling 3. A lead-free, alumina-free porcelain enamel having a firingtemperature range of between 900 F. and 1050" F. which consistsessentially of the following constituents calculated as weightpercentages:

Percent R 0 21-35 R 0 2- 5 R 0 '11-21 R0 44-50 where R 0 represents theoxides Na, K and Li; R O -represents the oxide of B; R 0 represents theoxides of P and vSb; and R0 represents the oxides of Si and Ti,

' wherein the ratio of the weight percent of Sb O tothe weight percentof B 0 is between 1.2 and 8.5, the summation of the weight percentagesof R 0, R 0 R 0 and R0 ingredients equalling 100%. p

4. A lead-free, alumina-free porcelain enamel having a r firingtemperature range of between 900 F. and 1050 F.

which consists essentially of the following constituents calculated asweight percentages:

where R 0 represents the oxides Na, K and Li; R 0 represents the oxideof B; R 0 represents the oxides of P and Sb; and R0; represents theoxides of Si and .Ti,

wherein the ratio of the weight percent-of SiO to the; weight percent ofTiO is between 0.8 and 1.3, the summa-: tion of the weight percentagesof R 0, R 0 R 0 and Percent 2 3 2.0- 5.0 Na O 9.5-16.0 K 0 10.0-18.0 i202.0- 6.0 1 18 20.0-27.0 2 s 1.0- 3.0 Sb205 10.0-18.0 sio 17.0 29,.0

wherein the ratio of the weight percent of SiO,-; to the weight percentof TiO is between 0.8 and 1.3, the ratio. of

the weight percent of 'Sb O tothe weight percent of B 0 is between 1.2and 8.5 and the Li O is about 9-18% of the total alkali oxide (Li O+NaO+K O) content, the':

tent, said total alkali oxide (Li O+Na O+K O) content being from 21-35%of the total composition.

- 6. A lead-free, alumina-free porcelain enamel havinsa Percentcalculated as weight percentages and totalling 100 weight 1 the weightpercent of Sb O to the weight percent of B 05 I percent:

Percent B 0 2.0- -,5,0 Na O 9.5-16.0 I K 0 f 10'.018.0' Li O "2.0- 6.0TiO 20.0-27.0 P205 3.0 I Sb O 10.0-18.0 SiO 17 .0-29;0

wherein the the weight percent a sio to the V weight percent of TiO isbetween 0.8 and 1.3,the ratio of .15

is between 1.2 and 8.5 and the Li Oiis about 9-18% of Y the total alkalioxide (Li O -|-Na 0+K O)]content,'the

Na O is about 3050% of the total alkali' oxide (Li O+Na 0+K O) contentand the K 0 is about 32- 56% of the total alkali oxide (Li O+Na O-l-.KO)' content, said total alkali oxide (Li O+Na O+K O) content being from21-35% of the total composition, and said SiO +TiO comprising from44%-50% of the total com position.

7. An article of manufacture comprising an aluminum workpiece containingas aprotective and decorative coating thereon the procelain enamel ofclaim 6.

References Cited in the file of this patent UNITED STATE S PATENTS2,492,523 r 2,537,956 Baldwin"; Jan; 16,1951

2,662,020 Schofieldet a1; Dec. 8, 1953' t 2,800,414 Stradlyetal. July23, 1 957 7 2,827,393

1. A LEAD-FREE, ALUMINA-FREE PORECLAIN ENAMEL HAVING A FIRINGTEMPERATURE RANGE OF BETWEEN 900*F. AND 1050*F. WHICH CONSISTSESSENTIALLY OF THE FOLLOWING CONSTITUENTS CALCULATED AS WEIGHTPERCENTAGES: